Development of the imaging system to evaluate of blood flow distribution and metabolic activity in myocardial microcirculation.

我们建立了荧光显微镜系统，用于心肌代谢活动和血流分布的成像。为了在活体条件下测量红细胞在微循环中的运动速度，研制了一套新的应用软件。在时间序列录像图像中沿着毛细血管设置线段，然后沿着该段构建时空图像。通过估计时空图像中反映红细胞运动速度的条纹图案的角度，计算红细胞运动速度矢量图。我们已经成功地定量评价在体内微循环与我们的视频显微镜系统和时空图像分析方法。局部心肌对缺氧的脆弱性是异质性的，然而，局部缺氧的动力学和局部缺氧对血流异质性的依赖性还没有很好的理解，特别是在微循环水平。因此，我们在氧合逐步变化的过程中评估了肌上皮细胞的NADH荧光，并将NADH荧光与血流分布进行了比较，将其分解为0.1×0.1 ~ 0.4×0.4 mm^2的区域，这些区域的大小与微循环单位相当，由单个毛细血管前小动脉灌注。在另一个显示稳定斑片状荧光模式的缺氧灌注心脏中，输注氚标记的去甲丙咪嗪，通过数字X线摄影测量肌外膜层内的相对流量分布。较高NADH荧光的区域倾向于接收较低的流量;区域流量-荧光相关性是显著的。这些结果表明，易患缺氧的地区也很难从缺氧中恢复过来，缺氧的区域脆弱性与微循环水平上的区域流动异质性高度相关。

We constructed the fluorescence microscope system for imaging of myocardial metabolic activity and blood flow distribution. To measure erythrocyte velocities in microcirculation under in-vivo condition with an intravital videomicroscope, the newly software was developed. A line segment was set along the capillaries in time-sequential videotaped images and then a spatiotemporal image was constructed along that segment. The angle of striped pattern in the spatiotemporal image which reflects the erythrocyte velocity, was estimated to compute erythrocyte velocity vector mapping. We have succeeded in quantitatively evaluating the in-vivo microcirculation with our videomicroscope system and by spatiotemporal image analyzing method. Regional myocardial vulnerability to dysoxia is heterogeneous ; however, the dynamics of regional dysoxia and the dependence of regional dysoxia on flow heterogeneity are not well understood, especially at a microcirculatory level. Thus, we evaluated epimyocardial NADH fluorescence during stepwise changes in oxygenation and made a comparison between NADH fluorescence and flow distributions, resolved into 0.1×0.1- to 0.4×0.4-mm^2 regions the sizes comparable to a microcirculatory unit, which perfused by a single precapillary arteriole. In another hypoxia-perfused hearts showing the stable patchy fluorescence pattern, tritium-labeled desmethylimipramine was infused and its deposition distribution, i.e., relative flow distribution within epimyocardial layers was measured by digital radiography. The region of higher NADH fluorescence tended to receive lower flow ; the regional flow-fluorescence correlation was significant. These results suggest that regions vulnerable to dysoxia are also hard to recover from dysoxia and that regional vulnerability to dysoxia is highly relevant to regional flow heterogeneity at a microcirculatory level.